264) Contributions to Electricity and Magnetism. 



Current of the third order . . . — 



Current of the fourth order . . . + 

 Current of the fifth order .... — 



93. In the first glance at the above table, we are struck 

 with the fact that the law of alternation is complete, except be- 

 tween the primary and secondary currents, and it appeared 

 that this exception might possibly be connected with the in- 

 duced current which takes place in the first coil itself, and 

 which gives rise to the pheenomena of the spiral conductor. 

 If this should be found to be minus, we might consider it as 

 existing between the primary and secondary, and the anomaly 

 would thus disappear. Arrangements were therefore made 

 to fully satisfy myself on this point. For this purpose the 

 decomposition of dilute acid and the use of the galvanometer 

 were resorted to, by placing the apparatus between the ends 

 of a cross wire attached to the extremities of the coil, as in 

 the arrangement described by Dr. Faraday (ninth series) : 

 but all the results persisted in giving a direction to this cur- 

 rent the same as stated by Dr. Faraday, namely, that of the 

 primary current. I was therefore obliged to abandon the 

 supposition that the anomaly in the change of the current is 

 connected with the induction of the battery current on itself. 



94. Whatever may be the nature or causes of these changes 

 in the direction, they offer a ready explanation of the neutral- 

 izing action of the plate interposed between two conductors, 

 since a secondary current is induced in the plate ; and al- 

 though the action of this, as has been shown, is in the same 

 direction as the current from the battery, yet it tends to in- 

 duce a current in the adjacent conducting matter of a con- 

 trary direction. The same explanation is also applicable to 

 all the other cases of neutralization, even to those which take 

 place between the conductors of the several orders of cur- 

 rents. 



95. The same principle explains some effects noted in re- 

 ference to the induction of a current on itself. If a fiat coil 

 be connected with the battery, of course sparks will be pro- 

 duced by the induction, at each rupture of the circuit. But 

 if in this condition another flat coil, with its ends joined, be 

 placed on the first coil, the intensity of the shock is much 

 diminished, and when the several spires of the two coils are 

 mutually interposed by winding the two ribands together into 

 one coil, the sparks entirely disappear in the coil transmitting 

 the battery current, when the ends of the other are joined. 

 To understand this, it is only necessary to mention that the 

 induced current in the first coil is a true secondary current, 

 and it is therefore neutralized by the action of the secondary 



